Previously, RF proximity fuzes have been utilized. However, larger projectile fuzes have typically required multiple piece nose cones where the user chooses a target selector switch setting at the time of launch depending on the desired target i.e., "ground" or "airborne". This requirement of user input before firing is time consuming and can lead to user error. The switch setting is necessary because radio frequency proximity fuzes are prone to false targets in certain "flat fire" scenarios. The false targets (clutter) may stem from trees, buildings, natural landmarks such as rocks and battlefield debris or hulks. False targets will cause detonation before the desired target is reached.
Further, traditionally, a radome is provided for RF proximity fuzes and is generally made of molded plastic material. However, the high tip temperatures of some projectiles in flight require a protective metal tip to dissipate the heat which would otherwise destroy the plastic. This complicates the assembly. Also, probable ablation of the plastic (charged during flight) would be a source of electrostatic noise which is not acceptable in the case of electrostatic proximity fuzing.
In order to avoid these problems and the need for a target selector switch, it is desirable to utilize a fuze sensor which detects the intrinsic electrical charge of an air-borne target. The electrostatic proximity fuze sensor minimizes false targets and is less vulnerable to countermeasures and clutter.
Electrostatic advanced development proximity sensors have been previously developed. The U.S. Army developed a proximity sensor in 1977 for use against helicopters. Also, General Electric was under contract with the U.S. Army to develop a helicopter proximity demonstration test sensor in the late 1980's. However, these sensors included relatively complex external probe configurations. The sensors were external dielectrically isolated annular nose cone electrodes, some with feed-through connections and EMI filters. External probe configurations lead to electrical interconnect problems. Because the sensor electrodes are external to the nose cone, the feed-through connections are required.
An electrostatic sensor nose probe/tip for "smart" munitions must withstand relatively high mechanical and thermal stresses during launch and flight. It also must be relatively nonconductive and nonablative. For some projectiles, setback forces during launch are 50,000 g's as the round accelerates to velocities approaching Mach 4 (1400 m/s). The boundary layer temperature near the tip of the nose cone reaches 1100.degree. C. within a few tenths of a second after launch. Ceramic materials are ideally suited for withstanding the stresses during flight and provide the required probe functionality.
Consequently, the need remains for an electrostatic proximity fuze for use in projectiles where the sensor is internal to the nose cone and which is able to withstand the conditions noted above. The present invention eliminates any electronic or environmental constraints allowing for a durable, reliable sensor which results in significant performance improvement for the projectile.
The art referred to and/or described above is not intended to constitute an admission that any patent, publication or other information referred to herein as "prior art" with respect to this invention. In addition, this section should not be construed to mean that a search has been made or that no other pertinent information as defined in 37 C.F.R. .sctn.1.56(a) exists.